This invention relates to a liquid fuel supply system for an atomization burner nozzle wherein the liquid fuel is supplied at a pulsing pressure characterized by supplying the nozzle with fuel at a continually-varying positive gauge pressure for a first period of time and interrupting the fuel supply during a second period of time. The pulsation pressure peaks are phased together with the pressure peaks of the natural pulsations occurring within the fuel pump structure to enhance the positive values of the pulsation pressure peaks and pump pressure peaks during said first period of time and the negative values of the pressure during said second period of time as well as the pressure rates of rise and fall, respectively, so as to minimize the time when positive sub-atomization fuel pressures are present at the atomizing nozzle.
Properly sized fuel oil fired heating systems for maximum efficiency are difficult to obtain for certain smaller-sized heating requirements, such as mobile homes, apartments, and small homes as well as larger dwellings during less severe heating seasons because of plugging problems with high pressure atomization nozzles. If the nozzle is sized sufficiently small for reduced delivery of fuel from the nozzle, it becomes subject to plugging by particulate material. Other methods of obtaining proper fuel flow rates, such as low pressure air-oil nozzles and sonic atomizers require other modifications to the heating system which add significant cost.
One system developed for delivering less than normal fuel through a nozzle is disclosed in Robert W. Erikson application Ser. No. 023,428, filed Mar. 23, 1979, now U.S. Pat. No. 4,255,093 and owned by the assignee of this application. In the structure of the Erikson application, the high pressure discharge from the pumping elements of the fuel pump is directed through a metering orifice open at timed intervals to provide a relatively low volume of flow to the burner nozzle, while avoiding the clogging problem.
A more recent system is that disclosed in James Harvey Moore Meyer application Ser. No. 165,565, filed July 3, 1980, and owned by the assignee of this application. In the method and structure disclosed in the Meyer application, the fuel is delivered to an atomization nozzle at a pulsing frequency which is dynamically matched to intermittent pressure pulses within the fuel pump to create resonant pressure peaks at the nozzle above normal regulated pressure with intermittent negative values of pressure to result in reduced flow of fuel through the nozzle.
It is also known in the art to supply fuel to an atomization nozzle from a fuel pump supplying fuel at a constant pressure and interrupting the delivery of fuel to the nozzle periodically to reduce the total rate of flow per unit of time through the nozzle by means of a rotatable member which blocks communication between the fuel pump and nozzle and during the blocked interval connects the nozzle to the pump inlet or source of fuel. Such a system does not provide a good workable system with high combustion efficiency at the nozzle.